Trucks and cabs pull trailers that often have tarp systems. Similarly, rail cars may have open top container cars for which tarp systems may be used. Tarps are known for covering contents of a container of the trailers and railcars during transport. Roll tarps often include a tarp attached on an axle, reel or roller and to a side of a container. Tarp systems are automated to cover trailers while transporting contents of the container. But size limitations, weight limits, efficiency, and output of motor and transmission must be maximized for tarp systems.
Apparatus have been devised for covering a truck load. Some such apparatus include an electric motor for selectively winding a flexible cover. U.S. Pat. No. 5,031,955 provides a truck cover that may be motor-operated from the cab of a truck to extend the cover from a winding assembly proximate the front of the truck bed and forward the rear of the truck bed. It discloses a direct drive spool winding system with an automatic self-brake feature with the 90 degree relationship of the worm gear with respect to the drive bolt threads.
Automated systems that cover the truck bed from side to side are known. For instance, U.S. Pat. No. 5,328,228 shows a cover for truck bed and cargo. Similarly, U.S. Pat. No. 5,924,758 shows a roll assist mechanism for tarp systems. U.S. Pat. No. 6,206,449, the disclosure of which is hereby incorporated by reference, shows a side-to-side truck cover system including a pair of arms, each of which includes a base and an extension.
Later Roll-Rite patents protect other aspects of a motor and knuckle arm assembly to unroll to open and to roll to close the tarp to uncover and cover the contents of a container of a truck or trailer.
U.S. Pat. Nos. 7,726,720 and 6,916,060 show a motor 30 mounted on the distal end of the extension 18. A rotatable reel 32 extends from the motor 30, and that is operatively connected to one end of the cover 12 so as to function as a take-up spool. The motor 30 is preferably provided with a brake, which allows, among other things, for the apparatus 10 to remain in the stowed or uncovered position. When the brake is released, the base 14 swings toward a side of the trailer or truck bed. The motor 30 may be powered, from within or without the cab of the truck, to facilitate operation. Further details of one embodiment of the motor are taught by U.S. Pat. No. 5,829,819, which is hereby incorporated by reference. In this way, the cover 12 is pulled off of the reel 32 and extended over the trailer or truck bed. The motor 30 can be reversed to drive the reel 32 and retract the cover 12 against the tension force of the springs to uncover the load bed.
U.S. Pat. No. 5,829,819 discloses a direct-drive actuator assembly that actuates a tarp spool for a truck bed tarp system. The direct-drive actuator assembly includes a transmission housing adapted for mounting to the tarp housing. An output shaft extends from the transmission housing for driving the tarp spool. An input shaft is also positioned at least partially within the transmission housing. An electric motor is operatively connected to the input shaft for actuating the tarp spool. The spur gear arrangement is not self-braking so a brake arrangement is used with the DC motor. A brake, such as a spring-loaded, power release type, is operatively connected to the electric motor for automatically braking the motor when the electric motor is turned off. A cover is provided for enclosing the stacked brake and electric motor against the transmission housing.
Automatic motor-operated solutions for tarp operation are known in the art. Electric motors are used with worm gears for roll tarp systems. In typical powered tarp systems, an electric motor may be used in conjunction with worm gears, which can be self-braking. Worm gears are inefficient. U.S. Pat. No. 5,829,819 discloses a series of rotatable transmission spur gears in a system with a secondary brake.
Trucks and trailers often have hydraulic systems to operate hydraulic components or other systems of the truck or trailer. Hydraulic systems have not been integrated with motors for roll tarp systems.
A higher efficiency, enhanced powered system in a compact, lightweight package is desirable.